共查询到20条相似文献,搜索用时 31 毫秒
1.
The radiation patterns of the dual mode horn and its related performance are influenced by the phase difference between component modes at the horn aperture and the phase distribution associated with the horn flare angle. Both effects are shown to deteriorate beam symmetry and increase sidelobe levels. Radiation pattern functions and fractional power distributions associated with the dual mode pyramidal horn are illustrated for a range of mode and distribution phase errors. 相似文献
2.
An improved multimode horn for Gaussian mode generation at millimeter and submillimeter wavelengths 总被引:1,自引:0,他引:1
An improvement on the dual-mode horn for Gaussian mode generation has been developed. Previous designs have used a sudden transition or linear taper to generate the required TE/sub 11/ and TM/sub 11/ mode mixture. In the improved design presented here, an optimized nonlinear taper is used to generate multimodes, which have a fundamental Gaussian mode power fraction of 99% that exceeds that of the corrugated horn (98%). The bandwidth and return loss are both improved over other dual-mode horn designs. 相似文献
3.
The far-field radiation pattern of a diagonal horn has been calculated by aperture integration. The radiation patterns for a 4×4 diagonal horn array, measured at 100 GHz, agree very well with theoretical predictions. The aperture electric field was also expanded into Gauss-Hermite modes. The results indicate that the fraction of the power radiated into the fundamental Gaussian mode is about 84%. About 10% of the power is radiated in the cross-polarized component 相似文献
4.
Quasi-optical 150-GHz power combining oscillator 总被引:1,自引:0,他引:1
Judaschke R. Hoft M. Schunemann K. 《Microwave and Wireless Components Letters, IEEE》2005,15(5):300-302
A quasi-optical power combiner for a five-element in-line oscillator array is experimentally investigated at 150 GHz. The combiner consists of a periodic dielectric phase grating (hologram) which transforms the near-field of a rectangular horn antenna array into a pseudo-plane wave. The horn array is excited by IMPATT oscillators operating uniformly in both amplitude and phase. A dual offset reflector set-up transforms the pseudo-plane wave to a Gaussian beam which matches the field pattern of a dual mode receiving antenna. Even though an inter-element spacing of 9.5 /spl lambda/ has been chosen, the passive structure gives a power combining efficiency of 74.1%. The power combining oscillator has been operated in both free-running and injection-locked mode. A CW output power of 78.0 mW and 83.5 mW was measured for the free-running and injection-locked oscillator, respectively, which is corresponding to a power combining efficiency of 66.5% and 71.2%, respectively. 相似文献
5.
Burkhard Plaum 《Journal of Infrared, Millimeter and Terahertz Waves》2018,39(10):984-995
This paper presents the optimization and characterization of broadband circular horn antennas with smooth walls. These antennas are simpler and easier to manufacture than corrugated horns. They work by converting the incoming fundamental mode to a mode mixture, whose total field corresponds to a Gaussian beam pattern at the aperture. The geometry of the horn is found by an optimization algorithm. While smooth-wall horn antennas have been designed for many years, they are inherently band limited because they rely on a correct multimode interference in the aperture to match the total field to a Gaussian distribution. The presented method achieves significantly larger bandwidths by allowing the Gaussian beam parameters, and thus the required mode spectrum in the aperture, to vary with the frequency. Together with an appropriate mirror optics, a receiver system with a bandwidth of more than 3 octaves could be realized. 相似文献
6.
Hui-Zhen Li Cheng-tian Xue 《Journal of Infrared, Millimeter and Terahertz Waves》1991,12(12):1437-1449
This paper describes a global optimization design of quasi-optics power combiner of solid-state millimeterwave resonator. It is operated in the frequency range from 50 to 300 GHz using GaAs Gunn diodes. It is shown that sourcearrays containing N2 (N=3,5,...2K+1, where k is positive integer) individual elements. It is very efficient power transfer of energy from the source-array to the fractional power of the fundamental beam mode etc.. The RF output power exceeded the sum of the individual diodes to be threefold to sevenfold. And this data is the global optimization solution. 相似文献
7.
J. A. Murphy M. McCabe S. Withington 《Journal of Infrared, Millimeter and Terahertz Waves》1997,18(2):501-518
Gaussian beam mode analysis can be applied in an elegant way to study the coupling of power between two horn antennas. Coupling efficiencies are evaluated for a number of horn combinations and the results presented in a straightforward form useful in the design of submillimetre-wave interferometers and astronomical receiver systems. We show that there is a marked variation in efficiency (up to 30%) depending on the coupling optics, even for beams with well matched profiles. 相似文献
8.
F. Tercero J. A. López Fernández E. García L. de Haro M. C. Carter A. Barcia B. Galocha J. L. Besada 《Journal of Infrared, Millimeter and Terahertz Waves》2003,24(5):669-681
The Beam Mode Expansion (BME) approach for corrugated conical feed horn plus meniscus lens is presented. This approach is useful for providing the radiation pattern as it propagates through an optical system. A developed theoretical model has been verified measuring near and far field of a built horn and lens. These results have been used for designing the optical system of a Cassegrain antenna at 100GHz using the fundamental Gaussian beam mode (GBM) of the new approach. Multimode analysis has been performed with the pre-designed system in order to test the fundamental GBM results. 相似文献
9.
Hui-zhen Li Xiang-wen Chen Si-we Lyu 《Journal of Infrared, Millimeter and Terahertz Waves》2001,22(6):905-915
This paper presents quasi-optics techniques, millimeter techniques and a global optimization method etc techniques. It is a structure of quasi-optics power combiner, that includes a spherical reflection, that the radius of the curvature is R and another one is a hybrid reflector that is called input reflector. The space of the both reflectors is LL. The monolithic source-array is made up of 25 Gunn diodes that are mounted of parallel brass bars that have low thermal resistance. And the bars are fixed on the inner plane surface of the hybrid reflector. The hybrid reflector made up of a plane and a spherical, that the radius of the curvature are R. It is designed that higher fundamental mode power, larger fractional power of fundamental mode power and more combining efficiency of the quasi-optics power combiner. This paper describes an algorithm, which can determine the global optima of the power combiner of solid-state millimeter wave resonator. The global optimization method can determine a neighborhood of the global optima of an objective function and an estimation of the global optima. In the quasi-optical resonator, the objective functions are the fundamental mode power, the fractional power of fundamental mode and the combining efficiency respectively. 相似文献
10.
Corrugated waveguide transmission lines are in use to transmit high power mm-wave radiation from gyrotrons to the plasma for
electron cyclotron plasma heating in tokamaks such as ITER. The coupling efficiency of the gyrotron output radiation formed
as a quasi-Gaussian beam to the waveguide mode is a critical issue. A hyperbolic corrugated horn serves as a converter of
the TEM00 Gaussian mode to the HE11 mode of a corrugated waveguide. We report the design of a hyperbolic horn for application in the ITER transmission line at
170 GHz. The theoretical conversion efficiency of the horn is higher than 0.995. 相似文献
11.
设计了一种新型太赫兹(THz)超高斯波纹喇叭天线。它由正弦曲线部分和线性平行部分组成,可同时激励起HE11和HE12两种模式。该天线工作的中心频点为0.34 THz,带宽大于40 GHz。在本文设计中,高斯基模的能量耦合效率可提高到99.8%。同时具有-37 dB的旁瓣电平和-50 dB的交叉极化特性。仿真和实测结果也表明此天线的优良性能,可以看出仿真结果与实测结果非常吻合。 相似文献
12.
Hui-zhen Li Xiang-wen Chen Si-wei Lyu 《Journal of Infrared, Millimeter and Terahertz Waves》1999,20(5):867-881
This paper presents a quasi-optical resonator that design methode basic on IBM PC computer (CAD). There is an exellent method to calculate global optima of the fundamental mode power, fractional power of the fundamental mode and combining efficiency etc. It also presents a process of CAD of microcomputer. 相似文献
13.
Adam Balkcum Richard Ellis Derek Boyd Samar Guharay 《Journal of Infrared, Millimeter and Terahertz Waves》1992,13(9):1321-1340
Linearly polarized fundamental mode Gaussian beams were generated and coupled to a hollow circular oversized dielectric waveguide by placing the waist of the beam at the guide entrance. The transmission properties of the waveguide were characterized as a function of frequency for a variety of coupling conditions. These conditions included changes in the input beam waist radius, angle of incidence, and displacement perpendicular and parallel to the guide axis. It has been found that: 1.) power transmission is maximized when the waist of the input beam is centered at the guide input, injected normally, and has a radius of 0.43 times the waveguide radius, 2.) power transmission decreases rapidly with increasing angle of incidence and the rate of that loss increases with frequency, 3.) the waveguide preserves the linear polarization of the input beam, 4.) power transmission in the fundamental waveguide mode is not greatly affected by moderate displacements in the input beam position, and 5.) upon exit from the waveguide the launched EH11 mode propagates as a fundamental mode Gaussian beam in the quasi-far field. The results compare favorably to the transmission theory of Belland and Crenn and approximately to the near and far field mode pattern theory of Degnan. 相似文献
14.
Phase centers of horn antennas using Gaussian beam mode analysis 总被引:1,自引:0,他引:1
The power of Gaussian beam mode analysis to accurately describe the propagation of electromagnetic beams and the location of a horn antenna phase-center is illustrated. By way of example, the case of a compensated pyramidal horn fitted with fins to produce a less abruptly tapered E -plane field distribution is discussed, and the results obtained are compared with those from an alternative method published in the literature. Excellent agreement is found 相似文献
15.
双棒串接补偿热致双折射效应激光谐振腔 总被引:1,自引:0,他引:1
固体激光器中的热致双折射效应严重地限制了基模输出功率的提高,为了获得大功率高质量的激光输出,需要对热致双折射效应进行补偿.在理论上对双棒在腔内串接补偿热致双折射效应的条件进行了改进,通过设计合理的腔结构和腔内元器件,应用4f成像系统空间滤波器并考虑石英旋光器的厚度,使得腔内光束的退偏率降至2.5%以下.使用矩阵光学的方法简化了对含有这样一个复杂光学系统的谐振腔稳定性和腔内光束半径等特性的分析.通过在腔内加入一个正透镜来扩大基模体积,实验中在双氪灯连续抽运Nd∶YAG激光器中得到了61 W线性偏振的激光基模输出,表明在大基模体积谐振腔的设计中,双折射效应的补偿十分必要. 相似文献
16.
The single fundamental mode output power of photonic crystal vertical cavity lasers is improved by varying sizes of oxide apertures and defect lasing apertures. A maximum output power of 3.1 mW in the fundamental mode has been achieved with a new fabrication process that involves only focused ion beam etching to create holes in selectively oxidised VCSELs. 相似文献
17.
用变分法导出了克尔型(Kerr—law)非线性阶跃型折射率光纤基模的传播常数公式结果表明,光束功率对基模的传播常数有显著影响。 相似文献
18.
19.
T. Idehara S. Mitsudo M. Pereyaslavets Y. Shimizu I. Ogawa 《Journal of Infrared, Millimeter and Terahertz Waves》1999,20(7):1249-1270
At certain gyrotron operating conditions, mode cooperation instead of mode competition takes place between a fundamental and a second harmonic mode. This means the phase bunching of a gyrating electron beam under the second harmonic operation reduces the starting current for the fundamental operation and increases total output power as well as beam efficiency. Such mode cooperation is observed in experiments and confirmed by computer simulations for submillimeter wave Gyrotron FU II. 相似文献